The organisers of a video game tournament based around the battle strategy title Hearthstone have been criticised for limiting entry to male players only.

The event, a Finnish qualifier for the World Hearthstone Championships, is taking place during the Assembly gaming exhibition in Helsinki at the end of July. A website page that provides information about entering the competition, originally stated "The participation is open only to Finnish male players."

The ruleset was re-posted by users of the social news service Reddit, provoking widespread derision. A spokesperson for the qualification heat, Markus Koskivirta told PC Gamer, "Your information is indeed correct, the tournament is open to Finnish male players only.

"In accordance with the International e-Sports Federation's (IeSF) tournament regulations, since the main tournament event is open to male players only. This is to avoid possible conflicts (e.g. a female player eliminating a male player during RO8) among other things."

Based in South Korea, the International e-Sports Federation presents itself as an international representative body for professional gaming. Formed in 2008, the body has arranged a series of major gaming tournaments around the world. On its Facebook page, the organisation states that its aim is "to promote e-Sports as true sports beyond barriers."

However, it seems that one barrier that has proven insumountable is gender. The IeSF splits entry into its world tournaments into male and female categories, so national qualification heats have to do the same.

Answering criticisms of its stance on the Facebook page, the organisation originally stated, "The decision to divide male and female competitions was made in accordance with international sports authorities, as part of our effort to promote e-Sports as a legitimate sports."

It later suggested that gender segragation would allow female players a chance to compete in what is a male-dominated sport. It aslo stated, "IeSF is very close to get (sic) e-Sports recognized as a true sports like it should be. Part of that efforts (sic) is to comply with the international sports regulations. For example, chess is also divided into male/female leagues."

However, the World Chess Championship, the game's major competition, is open to both men and women players – as are the top tier competitions in many non-physical sports.

As the controversy spread from social media to specialist gaming news sites, the stance seems to have softened. A new statement at the head of the Facebook page states:

"In the last hours we have received lots of feedback from you regarding the IeSF 6th e-Sports World Championship, particularly regarding the male/female tournament division.

"Our top priority is to promote e-Sports in the best ways we can. We believe that listening is important, and we're now collecting your opinions from the social media, and we will update soon."

Hearthstone is a fantasy strategy game in which players build decks of cards displaying various warriors with different skillsets – these decks are then used in turn-based battles against other players online. The game, which is developed by World of Warcraft creator Blizzard, has 10 million registered users.

E-sports is becoming increasingly popular around the world. Major tournaments in South Korea are televised to millions of spectators, while a recent championship event for the arena-based combat game League of Legends attracted enough spectators to fill Wembley Arena. Most tournaments do not segregate in terms of gender.

The Guardian contacted both the IeSF and Blizzard for comment, but none was received by publication time.